Furnace for producing purified metals



May 21, 1935. M. L. WOOD 2,001,803

FURNACE FOR PRODUCING PURIFIED METALS Filed Aug. 28, 1933' 3Sheets-Sheet l v Affornega 3 Sheets-Sheet 2 M. L. WOOD Filed Aug. 28,195-3 May 21, 1935.

FURNACE FOR PRODUCING PURIFIED METALS /m en+0r Naur/ce L, Wood 0 M,M*M4

Affarnegs May 21, 1935. M. L. WOOD FURNACE FOR PRODUCING FURIFIED METALSFiled Aug. 28, 1953 3 Sheets-Sheet 5 ,4 Howey;

Patented May 21, 1935 UNITED STATES PATENT OFFICE 2,001,808 FURNACE FORPRODUCING PUBIFIED METALS bury, Conn., a corpo Application August 28,1933, Serial No. 687,023

2 Claims. (CI. 13-29) This invention relates to improvements inproducing purified metals, and more particularly, metals such as copper,copper alloys and the like.

Heretofore in the production of copper and copper alloys, the finishedproduct frequently contained considerable amounts of non-metallicinclusions, oxides, etc. In particular, alloys containing appreciableamounts of aluminum or silicon or nickel are prone to give rise to theseimpurities. Needless to say, these inclusions are very detrimental tothe casting and to products fabricated therefrom.

It has been common in the art to cover the surface of the molten metalwith a layer of charcoal. While this layer of charcoal preventsexcessive oxidation, it is not particularly effective in cleansing themetal of oxide particles already present. Furthermore, when such moltenmetals covered with charcoal are poured in the ordinary manner from thetop, even with the greatest care to hold back the surface dross,

since the metal is poured from the top, these inclusions becomemechanically tangled in the raulting casting. Moreover, the layer ofcharcoal gives rise to gaseous impurities in the metal, namely, carbonmonoxide and carbon dioxide, which are formed from the burning of thecharcoal. These gases tend to produce holes and pockets in the castmetal.

30 One object of this invention, therefore, is to provide an improvedprocess for producing purified metals, whereby these non-metallicinclusions, oxides, etc., are substantially eliminated from the metals.

Another object of the invention is to provide an improved process forproducing purified metals, whereby gases such as carbon monoxide andcarbon dioxide are substantially eliminated there from.

Another object of this invention is to provide an improved apparatuswhereby the foregoing improved process can be readily and efficientlycarried out.

With the above and other objects in view, this invention includes all.improvements over the prior art which are disclosed in this application.

In the accompanying drawings, in which one way 01% carrying outtheinvention is shown for illustrative purposes: 50 Fig. l is a frontelevation of an induction furnace made. in accordance with thisinvention;

Fig. 2 is an elevation, mostly in section, on line 22 of Fig. l; andFig. 3 is an elevation, mostly line 8-4 of Fig. 2. v i

in section, on

The induction furnace I I has an-outer metal casing I I provided with alining I2 of electrical insulation. Within said insulation lining I2 isrefractory material II. The main chamber ll of the furnace is providedto hold the main body 5 of molten metal Ii. The pouring-spout I8 extendsfrom outside the furnace inwardly and downwardly to communicate with themain chamber II at the location I'I adjacent the bottom of the mainchamber. The opposite leg-portions or 10 leg-chambers I8 and I! extenddownwardly from the bottom of the main chamber I4 and are directedtoward each other at their lower ends so as to be joined together attheir lowest locations at to form a complete loop 2|. Thus, when 15 thefurnace is charged with metal, the molten metal not only occupies themain chamber H, but extends downwardly to fill the loop 2| formed by theleg-portions II and II.

Extending transversely through the loop por- 20 tion II is an iron core22 which will ordinarily be formed of laminations in the usual manner.The opposite ends of this core I! are preferably magnetically connectedwith each other by similar iron laminations 23, 24, 25, etc. Surroundingthe 25 core 22 is a coil 26 having a plurality of helical turns ofcopper ribbon or wire 21, as is usual. The coil 26 ordinarily issupplied with an alternating current of suitable frequency in thewell-known way. It, will be evident that the loop II of molten 30 metalforms a complete single turn of the secondary winding of a transformerof which the coil 26 formstheprimarywinding,allasiswell understood bythose familiar with the art of induction furnace construction.

Thetopofthesin'faceofthemetal Iliscovered witha layer of molten slag 2|.

In operation, the alternations of the electric current induce'a heavycurrent intbe loop ii of metal, causing considerable heating of thelegportions II, II thereof. Duepartly to this heating action in theleg-portions of metal which extend downwardly, and partly due to theviolent stirring action of the electric current, metal surges upwardlywith considerable speed and force from the leg-portions I I and I! inthe directions indicated by the upwardly-extending arrows (Fig. 3).Thus, molten metal is brought up from the depths of the bath of metalagainst the under side of the liquid slag layer a, thereby permitting Wthe slag to come in contact with the non-metallic inclusions andparticles of oxide, resulting in these inclusionaoxides, etc.,coalescing with or becoming entrapped in the slag layer, therebyresulting in the inclusions and oxides being eliminated from the body ofmetal and retained by the covering of slag.

This violent stirring action that takes place is continued until thesteady purifying action that takes place by the oxides and othernon-metallic inclusions contacting with and becoming entrapped in theliquid slag layer, results in the metal becoming substantially free fromnon-metallic inclusions, oxides, etc. At the same time that this removalof non-metallic inclusions is taking place, the liquid slag layer actsas aperfect blanket to prevent the absorption of gases by the metal, andas the slag itself contains no gases, as is true of charcoal, the metalis thus protected against absorption of gases.

After this purifying action has proceeded sufficiently to substantiallyremove the various objectionable inclusions, the metal is then pouredfrom the furnace into suitable molds through the pouring-spout l6.Inasmuch as this pouringspout I6 connects with the main chamber 14 onlyat a location well below the liquid slag layer 28, there is nopossibility of entraining or trapping any portion of the slag layer withthe metal during pouring, as would occur if pouring-spout l6 were solocated as to permit the top surface of the metal and slag to be pouredoff the metal into the molds. Thus, the finished product has a maximumdegree of purity, freedom from inclusions of non-metallic particles,slag, gases, etc.

The invention may be carried out in other specific ways than that hereinset forth without departing from the spirit and essentialcharacteristics of the invention, and the present embodiment istherefore to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced therein.

I claim:

I. A furnace for producing purified copper, copper alloys or the likecomprising: a main chamber for holding a quantity of molten metal; a legchamber of relatively-small cross-sectional area communicating with thebottom of said main chamber and extending downwardly therefrom; meansfor heating metal in said leg chamber; and a pouring spout communicatingwith said main chamber only adjacent the bottom thereof and well away toone side from the vertical planes enclosing said downwardly-extendmgleg-chamber.

2. A furnace for producing purified copper, copper alloys or the likecomprising: a main chamber for holding a quantity of molten metal; aloop chamber communicating with the bottom of said main chamber andextending downwardly therefrom; means for heating metal in said loopchamber; and a pouring spout communicating with said main chamber onlyadjacent the bottom thereof and well away to one side from the verticalplanes enclosing said downwardly-extending loop-chamber.

MAURICE L. WOOD.

